205 A/C + cooling fan relays
  • Help
Results 1 to 12 of 12
  1. #1
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default 205 A/C + cooling fan relays

    G'day all,

    I have had to rewire my fan relay circuit as the previous owner completely bypassed the thermoswitch on the radiator.

    Advertisement


    The current arrangement is the radiator thermoswitch controls both the relays (eg low speed at low temp, high speed at high temp). What I would like to know is where does the air con come into it? From what Cooling Fan say when the compressor is on, it turns the low speed relay on, and when high pressure is reached it puts the fans into high speed.

    Anybody know how the 205 was originally done, or what improvements could be made? Haynes wasn't helpful.

    Sent from my E6653 using aussiefrogs mobile app

  2. #2
    1000+ Posts
    Join Date
    Mar 2004
    Location
    Brisbane
    Posts
    1,809

    Default

    I will need to do likewise, the compressor input which will engage the clutch will need to be wired in parallel to the coolant switch that brings on the low speed, the high speed input will need to be wired to the pressure switch as well.
    87 S1 205 GTI / GTI6 powered a project underway
    306 convertible (gti6 candidate)
    307 HDi wagon
    407 HDi wagon

  3. #3
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,552

    Default

    Quote Originally Posted by flock View Post
    I have had to rewire my fan relay circuit as the previous owner completely bypassed the thermoswitch on the radiator.
    [/URL]
    Which model?

    And both versions have three relays.

    '92 205 Mi16
    '90 Mi16x4

  4. #4
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default

    Series 1 GTI, yes there are 3 relays sorry.

    I forgot to mention I have my thermoswitch positive from the ignition coil pos, but i was told that I should wire it straight from the battery so the fans can still run with the car off.

    Sent from my E6653 using aussiefrogs mobile app

  5. #5
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,552

    Default

    That's correct. Early Jetronic cars switch the relays to positive via the thermoswitch, whilst Motronic cars switch the relays to negative via the thermoswitch (Si included). Regardless, the fans (M635 & M636A) are wired like this, from a 1.9L Mi16, switched to negative via a Bitron controller(M891). If you're handy with wiring you'll be able to convert to positive switching. Relays are M733, M733A and M733B. It works like this:

    fans off <93
    low speed 93-98 - fans are connected in series
    high speed >98 - fans are connected in parallel
    Attached Thumbnails Attached Thumbnails 205 A/C + cooling fan relays-screen-shot-2016-10-25-8.59.48-pm.jpg  

    '92 205 Mi16
    '90 Mi16x4

  6. #6
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default

    Quote Originally Posted by PeterT View Post
    That's correct. Early Jetronic cars switch the relays to positive via the thermoswitch, whilst Motronic cars switch the relays to negative via the thermoswitch (Si included). Regardless, the fans (M635 & M636A) are wired like this, from a 1.9L Mi16, switched to negative via a Bitron controller(M891). If you're handy with wiring you'll be able to convert to positive switching. Relays are M733, M733A and M733B. It works like this:

    fans off <93
    low speed 93-98 - fans are connected in series
    high speed >98 - fans are connected in parallel
    Does the Bitron controller have an input from the AC or is that all the connections?

    Sent from my E6653 using aussiefrogs mobile app

  7. #7
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,552

    Default

    Yes, by supplying +12V to pin 11, via A/C dash button. I've only shown the fan part of the wiring diagram. While ever pin 11 is held high the fans will run at low speed. The same happens in a 205. ie

    A/C on - fans low speed
    >98 - fans high speed, regardless of whether A/C is on or not
    Last edited by PeterT; 25th October 2016 at 10:16 PM.

    '92 205 Mi16
    '90 Mi16x4

  8. #8
    1000+ Posts
    Join Date
    Mar 2004
    Location
    Brisbane
    Posts
    1,809

    Default

    Given fans operate independently corrcetly via thermo switch its two wires, one PeterT has identified is the AC from the switch, this wire must appear at the relay control point to start them on low speed, the high pressure switch likewise comes to the the high speed input point on the relays.

    Locating /finding them is the issue/problem! Not used to optimised wiring at work, uni yes just not at work and this is at a new level alltogether, think of it as the solution the supervisor presented you with after you struggled all day to get an answer.
    87 S1 205 GTI / GTI6 powered a project underway
    306 convertible (gti6 candidate)
    307 HDi wagon
    407 HDi wagon

  9. #9
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default

    In that respect since the jetronic does not have a Bitron controller. I am assuming there is a wire somewhere in my engine bay I haven't found yet from the aircon switch that is supposed to be in parallel with the switched positive from the thermoswitch into the low speed (left) relay and the high pressure switch is in parallel with both the changeover and other (right) relay to give high speed.

    Sent from my E6653 using aussiefrogs mobile app

  10. #10
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default

    Diagram for my sanity



    Sent from my E6653 using aussiefrogs mobile app

  11. #11
    1000+ Posts
    Join Date
    Mar 2004
    Location
    Brisbane
    Posts
    1,809

    Default

    I was just reminded a diode (power to hold 100mA not a signal diode) will be needed after AC switch before relay input, this stops a radiator temperature rise from bringing on the air con ie feedback.
    87 S1 205 GTI / GTI6 powered a project underway
    306 convertible (gti6 candidate)
    307 HDi wagon
    407 HDi wagon

  12. #12
    Fellow Frogger! flock's Avatar
    Join Date
    Feb 2014
    Location
    Brisbane, Australia
    Posts
    203

    Default

    Quote Originally Posted by Matthew View Post
    I was just reminded a diode (power to hold 100mA not a signal diode) will be needed after AC switch before relay input, this stops a radiator temperature rise from bringing on the air con ie feedback.
    I'm glad you brought that to my attention. Is the AC clutch fed straight from that switch?

    Sent from my E6653 using aussiefrogs mobile app

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •